Load Balancing in a Data Processing System Having Physical and Virtual Cpus

1. A method of load balancing in a data processing system comprising a plurality of physical CPUs and a plurality of virtual CPUs, the method comprising: mapping one or more virtual CPUs to each of said physical CPUs; determining, for a given virtual CPU, a negative load value indicative of the sum of the loads of all other virtual CPUs that are allocated to the same physical CPU as the given virtual CPU; and adapting the mapping of the given virtual CPU depending on the load of said physical CPUs and said negative load value.

2. The method of claim 1 , comprising: swapping the mapping only if the difference of loads of said first and second virtual CPUs is above a predetermined threshold.

3. The method of claim 1 , wherein the mapping of a first virtual CPU to a first physical CPU and the mapping of a second virtual CPU to a second physical CPU are swapped if the load of the first physical CPU is larger than the load of the second physical CPU, the load of the first virtual CPU is larger than the load of the second virtual CPU, and the negative load value of the first virtual CPU is above a predetermined threshold.

4. The method of claim 3 , comprising: running a multiprocessor operation involving said first and second physical CPUs; and assigning said first and second virtual CPUs to said multiprocessor operation, for executing said multiprocessor operation.

5. The method of claim 3 , comprising: swapping the mapping of the first and second virtual CPUs to the first and second physical CPUs, respectively, in response to a change of load of at least one of the first and second physical CPUs.

6. The method of claim 3 , comprising: determining the load of said first and second virtual CPUs; determining whether the load of said first and second physical CPUs is above a first threshold and below a second threshold, respectively; and swapping the mapping of the first virtual CPU to the first physical CPU and the mapping of the second virtual CPU to the second physical CPU if the load of the first physical CPU is above said first threshold, and the load of the second physical CPU is below said second threshold.

7. The method of claim 3 , comprising: running an operation of a high scheduling priority on one of said first and second physical CPUs, wherein said multiprocessor operation has a relatively lower scheduling priority.

8. The method of claim 7 , wherein the operation of a higher scheduling priority is executed by a dedicated real-time software.

9. The method of claim 7 , wherein said multiprocessor operation is executed by a generic server software.

10. A computer system, arranged to perform the method of claim 1 .

11. A computer program product stored in a non-transistory computer readable medium, which when executed by a data processing device, executes the method of claim 1 .